Process of making a cellulose material.



as have been devised vfor introducin barren STAThLSEirtTENT centers- CHARLES FREDERICK CROSS AND JOHN FREDERICK-BRIGGS, OF LONDON, ENGLAND.

PROGESS OF MAKING A GELLULOSE MATERBITAL.

no. ceases.

Specification of Letters Patent.

Patented May 4:, 1909.

Application filed September 16, 1907. Serial No. 393,190. (Specimens) T all whom i! may concern:

Be it known that we, CHARLES FnEDEIiIoK- Cnoss and Join: FREDERICK Braces, sub

jects of the King of Great Britain, residing ularly acetylated, cellulose exhibits as is known more or less resistance to direct cotton dyestuffs; it is less subject to the action of alkalies, as in the mercerizin process, and has a diminished attraction or atmospheric moisture. The advantages which can readily be foreseen as likely to accrue from such alteration in the properties of this textile material have never been realized, however, for the reason. that such processles t e radicals or groups'in question so attac the fibrous cellulose that it does not retain suflicient (if its original structure and strength to be suitable for spinning or weaving. As anexam 1c, the acetylating processes hitherto descri, ed have yielded as final products higher acetylated celluloses. These higher esters are soluble in chloroform, nitrobenzene, acetic acid, and other organic liquids; which property is an essential condition of their technical applications.

The properties of cellulose are considerably changed by, introducing into the compound various acid radicals; for instance by introducing organic acid radicals, notably the acetyl group, into cellulose, the behavior of the product varies from that of cellulose in many respects. Thus acidylated,, particularly acetylated cellulose exhibits as is 'known more or less resistance to direct cotton dyestufls; it is less subject to'the action of alkalies, as in the mercerizing process, and has a diminished attraction for atmospheric moisture. The advantages which can readily be foreseen as likely to accrue from such alteration in the properties of this textilematenal have, however, never been realized,

for the reason that such processes as have been devised for introducing the radicals or groups in question attack the fibrous eel-- lulose that it does not retain suflicient of its original structure and strength to be suitable for spinning or weaving. As an example, the acetylating rocesses hitherto described have yielded as final products higher acetylatcd celluloses. These higher esters are soluble in organic liquids, whichproperty is an essential condition of their technlcal applications. In the numerous inventions of recent years for preparing the higher acetic esters of cellulose, the reaction is preceded by hydrolysis of the cellulose, and this stage is recognized as determined by an auxiliary reagent, speci-,

fied as an essential component of the acetylating mixture. One of these methods is described as consisting in simultaneously hydrolyzing and acetylating the cellulose by treatment with acetic anhydrid and sulfuric acid or primary salts thereof or other mineral acids. This condition of acid attack im ports the -disintegration of the cellulose fibers more or less and hence excludes its applica tion to cellulose yarns or fabrics, or to fibers to be afterward employed in'textile menufactures. It has nevertheless been pro oscd to treat textile fabrics with such acctyiating mixtures, to produce a partial, in the sense of superficial, conversion of the cellulose into acetate. No indications are given for controlling the process in its industrial application.

The process according to the present invention is by contrast a conversion of the cellulose in the mass, free from the dangers of acid disintegration or weakening of the fibers limited definitely to thelower grades of acetylization, and married out under conditions which produce regular and definite products with a minimum consumption of reagents.

Our invention consists in a method of treating fibrous cellulose with appropriate known acetylating agents, in such a manner that it is converted into lower acetyl derivatives without prejudice to the textile qualities.

Our invention consists in treating fibrous cellulose with appropriate known aeetylating agents, in such amanner that it is converts into lower acetyl derivatives without prejudice to the textile (Equalities. of the fiber.

The process is applicable to the fiber itself, to .yarn or to woven or otherwise manufactured fabrics, and we thus obtain for the first time cellulose ester derivatives which while retaining the textile quality of the fiber or fabric, resist substantive cotton dyestuffs and can be subjected to alkaline lye in a inercerizing treatment without being sensibly altered.

We subject the cellulose to the limited acetylating action of acetic anh 'drid aided by a suitable saline assisting or condensing agent that has little or no effect on the fiber, such as zinc chlorid. A satisfactory criterion that the desired. acetylation has been attained is the increase in weight of the cellulose, which may be'from 15 to 50 per cent, according to requirements; the )roportion of the mixture of acetic anhydrid and zinc chlorid 'whichoth'e cellulose is allowed to absorb, as well as the extent to which the mixture is to be diluted with say glacial acetic acid or the like, are determined by the required degree of acetylation.

In carrying out the process we generally adjust the proportion of liquid to cellulose according to the absorption capacity of the raw material, so that the liquid is held uniformly dlstributed throughout the mass of cellulose. The degree of modification ultimately obtained is then regulated by var 'ng the proportion of the diluting agent in t e liquid.

As a specific example, assuming that cotton yarn or cotton 0 0th is to be acetylated so as to have the power of resisting direct cotton dyestuffs or mercerization, the thoroughly dried material is uniformly saturated with the liquid in such amanner that it retains approximately the predetermined quantit This quantity depends on the degree 0 modification required and therefore onthe percentage gain in weight of the cellulose. For a gain in wei ht of approximately 25 per cent. the dry ce ulose may be caused to absorb twice its weight of a mixture having the following composition.

Acetic anhyrid ..42 artsb wei ht, Acct lchiorid.... i? F Glac a1 acetic acid. ..5O Ignited zinc oxid 6. 5

art 0 the ce ulose may be caused to a sorb 2.3 parts of a mixture composed of Acetic anh drid ..66 artsb ht.

.Aeet ichldi-id ..11.5 p We); Giac a1 aceticacid ..32 Ignited zinc oxid 6.5

In preparing such mixtures the liquid const tuents are first mixed together and the zinc oxid is added in small quantities be substituted for the zinc oxid. For a gain in weight of ap roximately 33 per cent. 1 ll at a time, the mixture being stirred and cooled if necessary until the whole is dissolved.

When zinc chlorid is used as such, a suitable mixture is prepared by dissolving 20 parts of commercial zine chlorid in parts of glacial acetic acid and addiig to the solution arts of acetic anhydrid, these proportions eing suitable for obtaining a gain of weight amounting to 20-i0 per cent., according to the quantity used.

' It is to be understood that the degree of modification I solely upon t e degree of dilution of the reagent. Thus smaller proportionsof the more concentrated mixture will produce results equivalent to those obtained with a larger proportion of the more dilute mixture. In fact the proportions of acetic anhydrid zinc chlorid and acetic acid may be varied within wide 'limits according to the material treated and the degree of modification to be produced.

When the cellulose material has been saturated with the reagent, the action may be accelerated by packing the material in a closed vessel which is placed in a thermostat regulated at a temperature of 3540 C. After a period of 36-48 hours at this rial has been left at the ordinary temperature, the reaction is complete and the cellulose is removed and washed with Water until free from soluble products.

When it is desirable to prevent shrinkage the hanks of yarn or the fabric may be kept under tension during the treatment and during the washing also or during the washing only, if necessary.

When the cellulose is to be converted into a hard, nearly waterproof material, corresponding with a gain in weight of 405O per cent, it should be treated with 34 times its Weight of the more concentrated mixture, or with a smaller proportion of a mixture containing less acetic acid. in the former case the cellulose should be turned over from time to time during the progress of the reaction in order that the excess of liquid may be uniformly absorbed.

.Having thus described the nature of our said invention and the best means we know of carrying the same into practical effect, we claim:

1. As a new article of manufacture, lower acetylated derivatives of cellulose, insoluble in chloroform or nitrobenzene, made from fibrous cellulose, such derivatives having the characteristics of the original fibers that adapt the fibers for textile pur oses and being distinguished by resisting direct cotton dyestuffs and the action of mercerizing treatment.

2. In the process of making fibrous lower 'acetylated derivatives of cellulose from ee roduced is not dependent temperature, or a longer period if the matelulose fibers, the step which consists in treating fibrous cellulose with an appropriate acetylating agent until there is an increase in its weight not exceeding 50- per cent. without appreciable alteration of the textile qualities of the fiber, substantially as described.

3. In the process of making fibrous lower acetylated'derivatives of cellulose fibers, the ste which consists in subjecting the fibrous cel ulose to the action of a mixture of acetic anhydrid and a saline condensing agent 'that has no appreciable injurious effect on with a mixture of acetic anhydrid and zincchlorid suitably diluted with glacial acetic acid, then heating the saturated cellulose in 25 a closed,vessel at a temperature of 3540 (J. for some hours until the cellulose is converted into lower acetyl derivatives Without appreciable alteration of the textile qualities,

of the fiber, and finally washing and drying- 30 the material.

5. In the process of making an acetylating agent for the purpose herein defined, introducing acetyl chlorid and a zinc compound" capable of reacting therewith to form zinc 3.

ch orid, into a mixture containing acetic anhydrid and glacial acetic acid.

In testimony whereof We have signed our names to this specification in the presence of two subscribing witnesses.

CHARLES FREDERICK (moss. JOliN FREDERICK BRIGGS.

. Witnesses:

Josnrn WILLARD, I T. J. OSMAN. 

